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Astronomy

Impact of Earth’s Atmosphere on Optical Telescope Observations

The importance of visibility when making observations with an optical telescope may be an obvious consideration, but it can also be easy to discount the challenges faced in acquiring a clear image. One of the most potent barriers to optical telescope viewing is the atmosphere of the Earth (Chaisson & McMillan, 2011). Any astronomical observation is subject to the effects of the atmosphere as radiation must pass through it before it can be registered by an Earth-bound telescope. The air acts as a lens that prevents light from reaching an optical telescope at a flat angle and therefore distorts the image from any source outside of the atmosphere. Some common atmospheric effects include blurring and variations in brightness known as twinkling. This problem has been a target of research for much of the existence of optical telescopes, though it took the relatively recent development of launching telescopes into space to escape the effect in totality.

            The deformation of measurable object diameters is the most devastating effect of the atmosphere on observations made through an optical telescope. Diameter has historically been a key variable in the identification of celestial objects and the atmosphere causes refractive distortions that threaten the ability to reliably record such values. The primary cause of atmospheric refraction is the presence of turbulence and the resultant mixing of air components. Turbulence causes sections of air to flow in a way that impacts adjacent streams, resulting in apparent ripples throughout the atmosphere. These alterations can result in the blurs and twinkles that are common problems when making observations with an optical telescope.

            The degree of distortion caused by atmospheric turbulence is variable based on location and time. Accordingly, optical telescopes have been consistently placed in areas that are thought to be the least impacted by the atmospheric factor, such as those with low humidity like deserts and mountain peaks. The latter example has two qualities that are helpful in this cause as high altitudes reduce the amount of atmosphere that light must pass through before reaching the telescope. Additional steps have been taken to minimize this issue in the form of complicated techniques and tools known as advanced optics. However, not even these innovations are immune to the effect on a full-time basis. The development of the Hubble telescope helped to circumvent the confounding influence of the atmosphere completely, though deploying instruments outside of the atmosphere is not a simple task and thus will not be a widely available solution for some time.

            The atmosphere has had such a dramatic impact on astronomic optical imagery that humans have been forced to abandon the planet in order to achieve a desirable quality of representational accuracy. Though space bound telescopes like the Hubble offer the best image, there are several other techniques that allow for a much improved reliability in optical telescope viewing. However, these tools are similarly expensive and difficult to implement. It is possible that the most efficient approaches to the atmospheric problem will come from interferometry and its associated concepts. Turbulence in the air is a form of interference because it is essentially a pressure wave that is interacting with electromagnetic waves. Instruments called interferometers have been developed from this perspective and address the issue by observing the waves from multiple reference points that can then be used to deduce and reduce the impact of interference on visible waveforms.

Reference

Chaisson, E., & McMillan, S. (2011). Astronomy: A beginner’s guide to the universe. (6th ed.).             Benjamin-Cummings Pub Co.

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Astronomy

Interferometry and Problems in Radio Astronomy

The study of the universe would be extremely limited if the only available frame of reference was visible wavelengths. The waves that we interpret as visible colors only comprise a small portion of the entire radioactive spectrum. However, waves of all electromagnetic frequencies can potentially carry valuable information about the nature of the universe and observable reality. For example, radio frequencies have become useful in a manner of applications including serving as the foundation for an eponymous form of astronomy. Radio waves include those that oscillate at a rate of 3 kHz to 300 GHz and are plentiful throughout the observable universe. An assortment of celestial objects has been identified as sources of radio waves (Chaisson & McMillan, 2011) including stars, galaxies, quasars, and pulsars. The most famous source of radio emissions is the Big Bang and findings from radio astronomy helped to uncover the cosmic microwave background (CMB) which is theorized to have originated from the momentous event.

            Radio astronomy uses a variety of advanced tools and techniques to make telescopic observations of radio waves and their sources. However, despite continual advances in the field, much of the information gathered by these procedures would be lost if not for the application of radio interferometry. Interferometry is a group of techniques that employs the idea to reduce and ideally eliminate the effect of interference in readings of electromagnetic radiation. Interference occurs when waves interact to result in summations, subtractions, and other altered states that obscure the characteristics of the initial waveforms. This is a serious threat to the validity of electromagnetic data on every scale, especially that taken from distant sources as the waves have had more time and space to be altered by interference. Fortunately, the study of waves via interferometry can even account for complex interactions in most cases.

            The most important concept supporting the application of radio or other forms of interferometry is that of superposition, which refers to the combination of waveforms. The results of a vast number of wave interactions provide the framework for the application of interferometry as they allow for the identification and removal of changes to waves that have resulted in the form of those that are observed. Radio interferometry was developed in direct response to the difficulties that arose from excessive interference in radio wave observations that was otherwise only thought to be treatable by increasing the size of radio telescopes to unrealistic levels. Radio telescopes were difficult enough to use due to atmospheric resistance and the need to operate at high elevations. Tools known as radio interferometers were implemented to achieve this task by providing a number of reference points in the form of multiple radio telescopes. This system also provides increased signal volume and resolution, though it does require a large distance between telescopes and thus may face an expansion barrier over time.

            Radio astronomy has become a key part of many astronomical endeavors by providing information from a band of wavelengths that would otherwise remain unavailable for human observation. Like all forms of wave observation radio astronomy is prone to the effects of interference. The study of interferometry provides tools and methods to address this issue by examining the effects of superimposition on the observed waves. These influences can then be removed from the equation to reveal a closer approximation of the original waveform. Giant multi-telescope arrangements known as interferometers are used to collect the required information while advanced mathematic programs are used to determine and reduce the influence of interference on astronomical observations of the radio wave bandwidth.

Reference

Chaisson, E., & McMillan, S. (2011). Astronomy: A beginner’s guide to the universe. (6th ed.).             Benjamin-Cummings Pub Co.

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Astronomy

Lunar and Solar Eclipses

Most people on the planet are aware that both the sun and moon can appear to be blocked out at certain times. In both forms the event is known as an eclipse and is a type of syzygy, which is a term that is used to describe the nearly straight-line arrangement of three bodies in a single gravitational system. Eclipses can occur in many kinds of gravitational configurations and are not limited to our observations from Earth, though the terms lunar and solar eclipse are almost universally understood to be in reference to our own moon and sun respectively. Perhaps somewhat surprisingly, the similarities between solar and lunar eclipses are virtually non-existent beyond these fundamental characteristics. There are many important differences between these observable occlusions of the sun and moon that demonstrate the characteristics that are unique to each event Chaisson & McMillan, 2011).

            A lunar eclipse occurs when the moon passes through the shadow of the Earth. The gravitational arrangement in this situation has the moon on the far side of the Earth in reference to the sun. The Earth casts a shadow that obscures the sunlight that would otherwise illuminate the moon for regular viewing. Only a relatively small and especially dark central portion of the shadow known as the umbra can cause a total eclipse, while the larger outer segments of the shadow form the penumbra which is not completely free of solar radiation. A partial lunar eclipse occurs when only part of the moon is in the umbra and a penumbral eclipse refers to the darkening of the body while in the penumbra. A total penumbral eclipse is possible when the moon is still completely in the outer shadow, though the side closest to the umbra can still appear to be darker than the rest. Lunar eclipses are the most common to be observed by humans. This prevalence is based on many factors including the availability of viewing access from the planet, as lunar eclipses can be seen from the entire nighttime side of the planet. Also, the total eclipse can last for nearly two hours dependent upon the positioning of the planet, with partial coverage being present for up to four.  

            Solar eclipses are a much rarer observation than their lunar counterparts. A major reason for this scarcity is the fact that the moon is responsible for the occlusion when the relatively tiny body passes between the sun and Earth. The moon casts a shadow in this situation and a total solar eclipse occurs when the umbra reaches the surface of the Earth. The total eclipse will then only be seen by those who are within the area of the Earth covered by the umbra, which lasts for only a short time in any given spot. Should the small area fail to reach the planet then viewers directly in line with the moon would experience an annular eclipse where the sun appears as a bright ring around the smaller circular darkness of the moon. An especially rare solar eclipse is the hybrid type that describes a situation where the eclipse may appear to be annular from one vantage point but total from others. A partial solar eclipse is the most common form to be viewed because it can occur in the penumbra during total eclipse events and it can be the only observable result of a total eclipse when the umbra passes beyond the Earth’s poles. One of the most commonly known differences between solar and lunar eclipses is that you can safely look directly at an occluded moon while doing the same for a solar eclipse could cause serious eye damage.

            It can be tempting to assume that eclipses should occur on a monthly basis due to the orbit of the moon around the Earth. However, these events are far rarer in reality because our planet is not orbiting the sun on the same plane as the moon orbits the Earth. Accordingly, the three bodies will not form a straight line every pass as the moon may be above or below the plane of reference, and an eclipse of either type will not occur on a monthly basis.

Reference

Chaisson, E., & McMillan, S. (2011). Astronomy: A beginner’s guide to the universe. (6th ed.).             Benjamin-Cummings Pub Co.

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Astronomy

Discoveries of Galileo and Support for Copernicus

In the first half of the sixteenth century Nicolaus Copernicus developed the first thorough mathematical model of our solar system as a heliocentric arrangement. However, he was very aware of the resistance he would encounter from Church figures should his theory be published because it was in direct conflict with the traditional geocentric beliefs that are supported by scripture. Additionally, the science behind his theory was revolutionary for the period and Copernicus recognized that he would also be bombarded with criticisms from a variety of scholarly perspectives including philosophical inquiries. Despite his attempts to downplay the theory it would quickly spread by word throughout academic and related channels throughout Europe. Eventually Copernicus would consent to the publishing of his heliocentric model in his famous book De revolutionibus orbium coelestium. Copernicus would never have to face his fears of questioning as he died before it was released.

            Galileo Galilei became a champion of the Copernican heliocentric model in the early seventeenth century, coming to the defense of the theory as it had become subject to much opposition as the original author had predicted. Galileo found support for the theory through observations using a telescope (Chaisson & McMillan, 2011), one of the most advanced scientific instruments of the time and a luxury not had by his predecessor. The first discovery made by Galileo that favors the heliocentric model over geocentric was made shortly after the dawn of the seventeenth century. He observed that a star later identified as Kepler’s supernova moved in a manner that was incompatible with the theory of an immutable universe as held by the Aristotelian geocentric perspective. A few years later Galileo identified objects moving in line around Jupiter. He saw them disappear and reappear from behind the gas giant and laid the ground for the planet/moon model, a major astronomical discovery that was extremely supportive of the Copernican heliocentric system in comparison to geocentric theories by demonstrating that these objects were orbiting something other than the Earth.

            Further viewings of planets by Galileo gave even more evidence of deficiencies in non-heliocentric theories, though the astronomer may not have recognized much of it at the time. Saturn’s rings became a confusing mystery as they appeared to be orbiting moons from certain angles with some disappearing at apparently random intervals. Despite a lack of clarity about the nature of the objects, Saturn’s rings would come to represent another example of non-geocentric orbiting. Venus may have been the most significant of his planetary observations as it relates to support for the Copernican geocentric perspective. The existence of Venus’ perceived phases was in direct conflict with predictions from all forms of geocentric theories as well as other planetary models that were up for debate at the time. Accordingly, several transitional models emerged that combined both heliocentric and geocentric concepts to account for Galileo’s findings, each of which would eventually give way to purely heliocentric designs.

            The extent of Galileo’s various contributions to astronomy and physics through telescopic observations cannot be understated. However, one of the most prominent of his findings is that the Copernican heliocentric system is vastly superior to geocentric models in accounting for repeatable and testable observations of heavenly bodies. Even some of his more local investigations uncovered aspects in the moon phases and sunspots that further reduced the feasibility of any theory other than heliocentric being apt, while extremely distant stars and the dense clouds of the Milky Way presented a seemingly unending testing ground for future research that would also support the theory.

Reference

Chaisson, E., & McMillan, S. (2011). Astronomy: A beginner’s guide to the universe. (6th ed.).             Benjamin-Cummings Pub Co.

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Astronomy

Ecological/Evolutionary Model

In his book, Joralemon uses the “Ecological/Evolutionary” model to study the outbreak of cholera in a population. While the model as a whole tries to explore the relationship between humans and their environment, and how sickness interacts between the two, the model is also laden with evolutionary theory.  That is, the perspective uses the analytical lens of popular evolutionary concepts such as natural selection to examine the evolution in the relationship between bacteria (cholera) and its host (humans).  As a result, the model suggests relationships between what one sees in society and the level of environmental adaptation in that society.

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Astronomy

Our Inner Solar Planets

One of the most significant topics in science today is the exploration of the vast and endless solar system. The most recent and highly anticipated topic is the discovery of a new planet whose atmosphere mimics one like Earth’s. This is important because it is one of the many threats that could come about in the near or distant future. As the population continues to rise, Earth could one day hit its population limit and cause common peril. Improvements in medicine and industrial farming are causing a decrease in mortality rate and an increase in life expectancy. As population numbers grow, there will be an increase in degradation of the environment causing harmful side effects like increase carbon dioxide levels which could be linked to global warming. Another possibility is the destructive behavior we humans display every day. As the population increases so do the many hurtful activities like pollution, which taints water supplies, air purity, and soil quality. So, it is obvious why many companies and astronomers are determined to find more planets for humans to inhabit. A suitable atmosphere is critical to find the perfect planet. The primary atmosphere of terrestrial planets was once made of the gasses secreted during initial formation, “that is 94.2% Hydrogen, 5.7% Helium and everything else less than 0.1%” (Schombert). However, this primary atmosphere was lost on terrestrial planets due to multiple factors such as the surface temperature, atoms masses, and each planet’s escape velocity. The lighter atoms on the planets were able to move fast enough to reach escape velocity and leak out into space. The warmer terrestrial worlds do not contain hydrogen and helium in their secondary atmospheres. The elements that do remain are often contained in rocky minerals or packed ice. The terrestrial planets that we have in our solar system up to date include Mercury, Venus, Earth, and Mars.

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Astronomy

The Eyes in our Sky

One of Earth’s most incredible science instruments, the Hubble Space Telescope, is used as one of our forms of new knowledgeable information from space. According to Ray Villard, news director for the Space Telescope Science Institute in Maryland, the Hubble Space Telescope has provided us with well over 570,000 images and observed nearly 45,000 celestial objects to date (Villard), with its most recent achievement being its 29th year in orbit on April 24, 2019. The HST has been incredibly successful in providing astronomers with more and more information from space through its findings from the moment it was created, to the way it operates. This paper will give a detailed analysis of the history of the telescope and how it works. It will also show some of the interesting facts about it and the current discoveries associated with the glasses.